1. Field of the Invention
The present invention relates to a thermal transfer sheet and an ink ribbon, and particularly to a thermal transfer sheet being excellent in detachability between a non-transferable release layer and an image protecting layer and being capable of imparting a high glossy feel to prints.
2. Description of the Related Art
Protective layers composed of a thermoplastic resin are laminated on images formed on printing paper, for example, ink images formed by a sublimation thermal transfer method using sublimation or thermal diffusion dyes. The protective layers are imparted with gas cutoff performance and ultraviolet absorbing performance so that discoloration of images can be prevented, and transfer of inks which form images to various articles containing plasticizers, such as erasers and the like can be prevented.
A usual method for laminating a protective layer on an ink image is a method using a thermal transfer sheet. The thermal transfer sheet is prepared by stacking a non-transferable release layer, a protective layer, and an adhesive layer in that order from the sheet base material side. When the thermal transfer sheet is partially heated under pressure from the sheet base material side, a heated portion of the protective layer is transferred, together with the adhesive layer, as a protective laminate to printing paper.
In addition, a configuration in which solvent-insoluble organic fine particles are added to a protective layer has been proposed as a thermal transfer sheet capable of imparting excellent durability to ink images. The organic fine particles have an average particle diameter in a range of 0.05 μm to 1.0 μm and are added in a range of 150 to 2000 parts by weight relative to 100 parts by weight of a binder resin as a main component. As a result, the protective laminate transferred to an ink image and including the adhesive layer and the protective layer exhibits excellent film cutting property and an ink image covered with the protective laminated is imparted with excellent solvent resistance and durability (refer to Japanese Unexamined Patent Application Publication No. 11-105438).